Impaired vascular reactivity in newborn infants of smoking mothers.

A transcutaneous PO2 technique was used to study the influence of cigarette smoking during pregnancy on postocclusive reactive hyperaemia of the skin of newborn infants and their mothers. Forty-seven mothers and their infants were studied on two occasions (24-48 and 96-144 h) after birth. Twenty of the mothers were habitual smokers, 27 were non-smokers. All mothers were healthy and their pregnancies and deliveries were normal. The infants were all healthy throughout their first week of life. The mothers had more marked reactive hyperaemia than their newborn infants (p less than 0.001). Infants of smoking mothers had a significantly weaker postischaemic hyperaemic response 24-48 h after birth than infants of nonsmoking mothers (p less than 0.01). This difference had disappeared 96-144 h after birth. Smoking mothers also showed a significantly weaker hyperaemic response to ischaemia than the control mothers at the first investigation (p less than 0.05). This difference was smaller and not statistically significant at the second recording. A decreased capacity for postocclusive reactive hyperaemia might be particularly harmful in asphyctic infants, but it may also be detrimental for a normal postnatal circulatory adaptation.